Graduate overlay-aware CodeQL version selection

[henrymercer]

Graduate overlay_analysis_match_codeql_version and remove the overlay_analysis_match_codeql_version_dry_run dry run, along with the telemetry diagnostic added for it. GHES is excluded explicitly since there are no feature flags and therefore only one CodeQL version will ever be enabled there. Also, as a small optimisation, skip listing the Actions cache when only one default CodeQL version is enabled, since there is only one CodeQL version to choose in this case.

Risk assessment

For internal use only. Please select the risk level of this change:

• Low risk: Changes are fully under feature flags, or have been fully tested and validated in pre-production environments and are highly observable, or are documentation or test only.

Which use cases does this change impact?

Workflow types:

• Advanced setup - Impacts users who have custom CodeQL workflows.
• Managed - Impacts users with dynamic workflows (Default Setup, Code Quality, ...).

Products:

• Code Scanning - The changes impact analyses when analysis-kinds: code-scanning.

Environments:

• Dotcom - Impacts CodeQL workflows on github.com and/or GitHub Enterprise Cloud with Data Residency.

How did/will you validate this change?

• Unit tests - I am depending on unit test coverage (i.e. tests in .test.ts files).

If something goes wrong after this change is released, what are the mitigation and rollback strategies?

• Rollback - Change can only be disabled by rolling back the release or releasing a new version with a fix.

How will you know if something goes wrong after this change is released?

• Telemetry - I rely on existing telemetry or have made changes to the telemetry.

Are there any special considerations for merging or releasing this change?

• No special considerations - This change can be merged at any time.

Merge / deployment checklist

• Confirm this change is backwards compatible with existing workflows.
• Consider adding a changelog entry for this change.
• Confirm the readme and docs have been updated if necessary.

[Copilot]

Warning

• Copilot's review of this pull request may be incomplete because some of the changed files are excluded by your Copilot content exclusion settings. See Excluding content from Copilot for details.

🔵 Needs a closer look

A maintainer should confirm rollout readiness before removing the feature-flag kill switch.

1 open finding

• Remove redundant empty-list guard · New

What changed in this PR

Graduates overlay-aware default CodeQL version selection for eligible Code Scanning pull requests.

Changes:

• Removes feature flags, dry-run behavior, and diagnostic telemetry.
• Skips cache lookup on GHES and when only one default version is enabled.
• Updates regression coverage for selection eligibility.

File	Description
src/​setup-codeql.ts	Graduates selection and adds cache-lookup guards.
src/​setup-codeql.test.ts	Covers supported environments and bypass conditions.
src/​feature-flags.ts	Removes selection and dry-run flags.

Files excluded by content exclusion policy (1)

• lib/entry-points.js

🧠 Review effort: Max

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